Fix missing write in TTStreamWriter::printf.

I don't think it is possible to exercise the failing codepath except
with artificial fonts having extremely long metadata entries, but the
missing write is clear from the context.

Author: anntzer

extern/ttconv/ttutil.cpp

@@ -45,6 +45,7 @@ void TTStreamWriter::printf(const char* format, ...)
 #else
     vsnprintf(buffer2, size, format, arg_list);
 #endif
+    this->write(buffer2);
     free(buffer2);
   } else {
     this->write(buffer);